package com.jh.recordaudiodialog.recorder;

import android.media.AudioFormat;

import omrecorder.PullableSource;

/**
 * Created by jh352160 on 2018/8/9.
 */
public class WavHeader {
    private final PullableSource pullableSource;
    private final long totalAudioLength;

    WavHeader(PullableSource pullableSource, long totalAudioLength) {
        this.pullableSource = pullableSource;
        this.totalAudioLength = totalAudioLength;
    }

    /** Returns the {@code WavHeader} in bytes. */
    public byte[] toBytes() {
        long sampleRateInHz = pullableSource.config().frequency();
        int channels =
                (pullableSource.config().channelPositionMask() == AudioFormat.CHANNEL_IN_MONO ? 1 : 2);
        byte bitsPerSample = pullableSource.config().bitsPerSample();
        return wavFileHeader(totalAudioLength - 44, totalAudioLength - 44 + 36, sampleRateInHz,
                channels, bitsPerSample * sampleRateInHz * channels / 8, bitsPerSample);
    }

    private byte[] wavFileHeader(long totalAudioLen, long totalDataLen, long longSampleRate,
                                 int channels, long byteRate, byte bitsPerSample) {
        byte[] header = new byte[44];
        header[0] = 'R'; // RIFF/WAVE header
        header[1] = 'I';
        header[2] = 'F';
        header[3] = 'F';
        header[4] = (byte) (totalDataLen & 0xff);
        header[5] = (byte) ((totalDataLen >> 8) & 0xff);
        header[6] = (byte) ((totalDataLen >> 16) & 0xff);
        header[7] = (byte) ((totalDataLen >> 24) & 0xff);
        header[8] = 'W';
        header[9] = 'A';
        header[10] = 'V';
        header[11] = 'E';
        header[12] = 'f'; // 'fmt ' chunk
        header[13] = 'm';
        header[14] = 't';
        header[15] = ' ';
        header[16] = 16; // 4 bytes: size of 'fmt ' chunk
        header[17] = 0;
        header[18] = 0;
        header[19] = 0;
        header[20] = 1; // format = 1
        header[21] = 0;
        header[22] = (byte) channels;
        header[23] = 0;
        header[24] = (byte) (longSampleRate & 0xff);
        header[25] = (byte) ((longSampleRate >> 8) & 0xff);
        header[26] = (byte) ((longSampleRate >> 16) & 0xff);
        header[27] = (byte) ((longSampleRate >> 24) & 0xff);
        header[28] = (byte) (byteRate & 0xff);
        header[29] = (byte) ((byteRate >> 8) & 0xff);
        header[30] = (byte) ((byteRate >> 16) & 0xff);
        header[31] = (byte) ((byteRate >> 24) & 0xff);
        header[32] = (byte) (channels * (bitsPerSample / 8)); //
        // block align
        header[33] = 0;
        header[34] = bitsPerSample; // bits per sample
        header[35] = 0;
        header[36] = 'd';
        header[37] = 'a';
        header[38] = 't';
        header[39] = 'a';
        header[40] = (byte) (totalAudioLen & 0xff);
        header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
        header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
        header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
        return header;
    }
}
